Which maintenance command removes obsolete files while respecting a retention policy in Delta Lake, helping reclaim storage without discarding needed data?

Which maintenance command removes obsolete files while respecting a retention policy in Delta Lake, helping reclaim storage without discarding needed data?

• A. VACUUM with retention
• B. OPTIMIZE
• C. ANALYZE
• D. COMPACT

Answer: (A)

VACUUM with retention removes obsolete data files from a Delta table, but only after they fall outside the defined retention window. This means Delta Lake can reclaim storage space by deleting files that are no longer part of the current state, while still preserving data for time travel or rollback within the retention period. This balance—cleaning up unused files while guarding against data loss—is what makes it the appropriate maintenance operation. Other options target different goals: OPTIMIZE focuses on merging small files to improve performance, ANALYZE gathers statistics for query planning, and COMPACT isn’t a standard Delta Lake maintenance command for cleaning up files.

VACUUM with retention removes obsolete data files from a Delta table, but only after they fall outside the defined retention window. This means Delta Lake can reclaim storage space by deleting files that are no longer part of the current state, while still preserving data for time travel or rollback within the retention period. This balance—cleaning up unused files while guarding against data loss—is what makes it the appropriate maintenance operation.

Other options target different goals: OPTIMIZE focuses on merging small files to improve performance, ANALYZE gathers statistics for query planning, and COMPACT isn’t a standard Delta Lake maintenance command for cleaning up files.